This invention relates to a rewritable optical information recording carrier which utilizes a phase change between a crystalline state and an amorphous state, and more particularly to an optical information recording carrier having distinguished characteristics of repeated recordings and erasings.
The conventional optical recording carriers of phase change type use organic members such as replica-formed disk substrates of ultraviolet-curable resins, injection-molded plastic substrates, etc. In order to prevent the recording film from deformation or evaporation during the recording or erasing, the recording film is further protected with a transparent inorganic film, which is typical of a SiO.sub.2 film. That is, the recording film of phase change type is sandwiched between transparent protective films of inorganic material, which are further covered each with an organic layer on the outside. These types of optical information recording carriers are disclosed, for example, in Japanese Patent Publication No. 52-2783, Japanese Patent Application Kokai (Laid-open) No. 60-38746, etc.
When the conventional optical information recording carrier of phase change type is exposed to a laser beam to carry out recording or erasing, the temperature of the recording film of phase change type will be increased to higher than the melting point and also the temperature of the organic layers will be increased approximately to the melting point of the recording film, so that the organic layers are much liable to undergo deformation or deterioration. In other words, deformation or deterioration of the organic layer will be increased and accumulated as the recording and erasing are repeated, and ultimately recording, erasing or read-out by light cannot be continued.